Hereditary Cataracts (HC) – Posterior Polar Cataracts
- Info
- Health Screening
- Buyer Advice
- Breeder Advice
- How You Can Help
What is HC?
A Cataract is an opacity (cloudiness) of the lens or it’s capsule, there are a number of different types of Cataract classified by where in the lens they first develop. The most common type of Hereditary Cataract in the Giant Schnauzer is the Posterior Polar Sub-capsular Cataract (PPSC), ‘polar’ refers to the centre, and ‘posterior’ means at the back. PPSC is typically seen as a small triangular or inverted ‘Y’ shaped opacity which is often bilateral (in both eyes), and found at the back of the lens. On 1st January 2004 Giant Schnauzers were placed on Schedule A of the Kennel Club/British Veterinary Association eye scheme, after Cataracts were thought to be hereditary.
Prevalence
3% of Giant Schnauzers, that have been eye tested and results recorded with the UK Kennel Club, are affected with Hereditary Cataracts.
Giant Schnauzers were placed on Schedule A of the KC/BVA/ISDS Eye Scheme on 1/1/2004, up to the end of 2018 there were 16 Giants that have been eye tested and found to be affected with HC. The graph below shows eye tests undertaken for both affected and unaffected Giant Schnauzers. The red dotted trend lines shows that the number of affected dogs has remained constant between 0-3 cases per year since eye testing for HC was added to schedule A of the BVA/KC eye scheme.
Age of Onset
PPSC can occur at any age, cases have been reported ranging from just over 12 months to over 7 years. This type of Cataract doesn’t appear to be congenital in the Giant Schnauzer, i.e. puppies do not seem to be born with PPSC.
Mode of Inheritance
It is currently not known how HC is inherited in the Giant Schnauzer, further research is required to determine the mode of inheritance.
Signs & Symptoms
In most instances there are no noticeable signs or symptoms, the eyes appear perfectly bright and clear, and usually there is no obvious effect on vision. This type of Cataract is currently not thought to progress in the Giant Schnauzer, although more research may be required.
Diagnosis
A Cataract is most often diagnosed at a routine eye examination. Eye examinations are a requirement for breeders under the Kennel Club Assured Breeder Scheme. Before breeding all Giant Schnauzers should hold a current clear eye certificate, which is renewable annually. Any dog can be tested under the BVA/KC or ECVO scheme. A list of eye examiners and their locations can be found on the following links:
Find an eye panellist online search
Prognosis
Apart from breeding, Giant Schnauzers affected with HC may otherwise live a perfectly normal life and continue with their usual activities, sports, working etc. No treatment is generally required, however it is advisable to monitor any changes. If the cataract is hereditary, it would be useful to ask the vet to take a cheek swab sample, alternatively cheek swabs can be obtained from the breed health co-ordinator. Should it progress, please let us know for future reference.
KC/BVA/ISDS Eye Scheme
Breeders are required to eye test breeding stock annually for Hereditary Cataracts.
For over 30 years the BVA has operated a hereditary eye disease screening programme in conjunction with the Kennel Club (KC) and the International Sheep Dog Society (ISDS). The scheme covers HC in the Giant Schnauzer as well as hereditary eye conditions in over 50 breeds of dog.
The main purpose of the scheme is to ensure that there is no evidence of hereditary eye disease in dogs used for breeding. Breeders are required to submit dogs for annual eye tests, since HC can have late onset of clinical signs.
Where to go for an Eye Test
Eye testing is carried out by specialist ophthalmology vets who are listed on the BVA panel of examiners.
Find an eye panellist online search
Requirements for the Eye Test
1. Before certification dogs should be permanently identifiable by microchip or tattoo.
2. Registration documents are required on the day of the eye test.
Costs
Up-to-date information on the current cost of eye testing can be found on BVA cost of submissions and examinations which includes a full breakdown of reduced fees for older dogs and group examinations.
Publication of Results
The Kennel Club is responsible for publishing the results in the Kennel Club Breed Records Supplement, on progeny registration certificates and on the Kennel Club health results database.
Advice for Puppy Buyers
Choose a breeder where the dam and sire of the litter have been eye tested within the last year.
To minimise the chances of a puppy becoming affected with Hereditary Cataracts, it is advisable to check that both parents hold a current, clear eye test certificate. Each dog is issued with an eye test certificate by a specialist eye panellist vet, and because cataracts can occur at any age, the eye test certificate is valid for 1 year only. The breeder should be able to show you the up-to-date eye test results of the puppy’s parents and will be happy to talk to you about the results, and any other health related issues. Although this cannot guarantee that a puppy will not develop Hereditary Cataracts, it will help to reduce the risk of purchasing a puppy that may become affected later.
Kennel Club Health Test Result Finder
If you know the name of the puppy’s parents you can look up the eye tests results and any other recognised KC/BVA health tests via the Kennel Club Health Test Results Finder. You may also ask the breeder to show you the eye certificates of the puppy’s parents.
Breeders are required to eye test breeding stock annually for Hereditary Cataracts.
Find an eye panellist online search
Giant Schnauzers are currently listed on Schedule A of the KC/BVA/ISDS Eye Scheme for Hereditary Cataracts. All breeding stock should be eye tested annually before breeding takes place. The sire and dam should hold a current, clear eye certificate to ensure they are clinically unaffected at the time of mating. Additionally, since the age of onset can occur later in life, it is advisable to continue eye testing into old age.
Unfortunately the mode of inheritance for HC in the Giant Schnauzer has not yet been identified. Currently it is only by eye testing dogs and bitches on an annual basis, that it is hoped to try and keep the incidence of HC at a low level.
If a dog is diagnosed as ‘Affected’, please forward DNA cheek swab samples to the Animal Health Trust for future research. In this way it may be possible for a DNA test to be developed that will enable dogs to be bred from more ‘safely’ in the future.
Research into HC
The Kennel Club Genetics Centre currently store cheek swab samples from dogs affected with Hereditary Cataracts, which may be used in the future to determine the responsible gene mutation, with the possibility of a DNA test in the future. A minimum of 18 samples are required for an initial genome scan and currently they hold DNA swabs for around 9 Giants. Therefore if anyone owns an affected dog it would be helpful to send a cheek swab. A genome scan will also require funding and it is hoped that the Giant Schnauzer Health Fund may go towards this purpose should the required number of samples be achieved.
If you Own an Affected Dog
Please send a simple DNA sample to the Kennel Club Genetics Centre, this can be done by using a cheek swab on the inside of your dogs mouth and posting it back to the KCGC.
Cheek swab kits can be obtained from the breed health co-ordinator
Email: bhc@giantschnauzerhealth.org.uk
Make a Donation to the GSHF
The purpose of the GSHF is to provide monies for research into inherited health problems in the Giant Schnauzer. All donations gratefully received.